Don't know if this topic has been brought up before, but here is what I found out to finish an install.

Each line requires at least 24 volts to operate, the LEC or CLEC gives out a nominal 48 volts DC at a tiny amperage.

For paging you need a Valcom 2000A (newest model) or an old Valcom 2000 that is sitting around. The switch needs to be set to provide 24 Volts DC on the line.

You plug a modular cord from the chosen line input (in my case line six) to the Valcom 2000. A pair of wires goes from the signal output to the amplifier or to the lead of amplified page units.

It is possible Viking or someone else makes a unit that serves the same purpose as the Valcom 2000A but that unit is a for sure working application.

The Valcom has an adjustable volume control but you also can control the volume on the Amp input control or the main volume adjustment on the Amp.

THE Bracha, old blond specialist in Rube Goldberg solutions.